Valve-gear



2 sneens-slhe'en 1.

(No Model.)

S. E. CRAWFORD.

VALVE GEAR.'

No. 321,583. Patented July 7, 1885.

Unteren Smarts artnr @trice SAMUEL E. CRAVFORD, OF RIPON, VISCONSIN.

VALVE-GEAR.

Application filed April 21.; 18.25.

T f/,ZZ whom it' may concern:

Be it known that I, SAMUEL CRAWFORD, a citizen ofthe United States, residi ng at Ripon, in the county of Fond du Lac and State ofViscousin, have invented certain new and useful Improvements in Valve-Gear for Steam-Engines, of which. the following is a specification, reference being had therein to the accompanyi ng drawings.

My invention relates to that class of cut-offvalve gear which operates automatically by the speed of the engine acting npon a centrifugal governor attached to the main engine-shaft; and the object is to produce a very sensitive, positive, and reliable valve gear that operates and at the saine time regulates the opening and closing ofthe valves according to the increase and decrease of the speed of the engine and the load to be acted upon, thus per forming such operation in an automatic manner, and that without the necessity of the attendant adjusting any of the valve-gear by hand to suit the varying speed of the engine; and it consists in the construction and arrangement ofthe opera-ting parts, as will be fully hereinafter described.

In the drawings like letters indicate the salue or silnila-r parts in the several different tigules, ill which- Figure l represents an upright olle-side View ofthe devices that govern the cut-off valves as attached tothe engine shaft or wheel; Fig. 2, a view of the devices upon the opposite side of the wheel. Fig. 3 is a side View of Fig. l with the parts in a changed position relatively. Fig. 4 is a cross-section on line a:

x ofFig. 3. Fig. 5 is aside view of an actuating-cani, and Fig. 6 is a side view of a segmental ealn.

A represents a disk or wheel permanently secured to the crank-shaft A', revolving with the said shaft,and having a lia-nge, a, at aright angle with the body or web of the wheel and projecting from the web far enough to receive and have secured thereto the guide-rods a and metal brackets c upon opposite sides.

B B are springs ot' any suitable forni; butin this instance they are plate-springs elliptical ill forni.

Il b are parallel rods. One end of each is secured in one of the brackets o, while the other ECFECATIGN forming part; of Letters Patent No. 321,553, dated July '7, 1885.

(No modi-1.)

end of such rod is attached centrally to a spring, B, as seen in Fig. 9.

C C are weights of any suitable forni, constructed to freely slide upon the guides a a toward or from the crank-shalt. TWeights C are attached to the ends of sprillg B by the links c, that allow the weights to move from shaft A when the force that causes such movement is greater than the power of the spring; but when such force is withdrawn or suspended the power in the springs should be sniiieient to bring the weights back toward the shaft to their normal positions.

B' B are parallel-toothed racks, one end of each securely attached to a weight, C, as seen in Fig. 2, and far enough apart to receive the toothed pinion D,tllat is secured to the crankshaft, and have the teeth of the pinion gear into the teeth on the racks.

Pinion D has all arnl, D', extending radially a distance from its periphery, and toward its outer end is a curved slot, d, in which is a friction-roller, d', that is secured around bolt d", which roller moves backward and forward in the variation of the movement of the engine. The holt d passes through the web of Wheel A, and has a segment, E, that forms ay movable cam by means of said bolt d passing through the segment at x and on the opposite side of the web of wheel A. This segmental cam nieves in and ont as the speed of the en gine varies, and in its outward movement is carried into the passage or way e against the spring e and outward from the concentric circle E. The inner edge of said segment E forms part of the eam-groovef.

F is a cam, secured by a bolt, .f/, that passes through the web of' wheel A and through the arm D of pinion D, and in connection with the circle or ring E and segment E, the calngroove f, in which groove the rollers .7l and Il' on the valve-stems i and t travel and open and close the valves as the speed of the wheel A or the engine varies, being connected to the valve-stems that actuate the valves. A curved slot, e', in cam F serves as a gnidcway to bolt g as the pinion with its arm D moves in one or in the opposite direction.

To change or adjust the point of contact of the cam and rolls on the valve-stems 'i and k and adjust or limit them in their movements, two

ICO

links or rods, Z and m, are attached to the valve-stems, Fig. l, and pivoted at their opposite ends to the engine-bed or to some other ixed part, and are made adjustable by the use of turnbuckles n a,having right and left hand screws,in the usual way of such adjustments. The exhaust-valves may be operated by any known cam or eccentric, and as there should be always a free or open exhaust of the steam to prevent back-pressure, they are arranged to permit the exhaust-steam to escape freely and quickly. The friction-rollers that are attached to the valve-stems that operate the cutoff valves work in groove f, and as the motion of the engine increases the weights are forced apart, or when the motion decreases the springs will overcome the centrifugal force, that the greater speed of the wheel induced and force the weights back toward the center,

for'in this movement the segment and cam form a perfect circle, and the valves are then stationary. The opening of the valves also commences at the same point, and will not be opened to their full extent, which is not necessary, as the piston travels slowly in the beginning, and increases in speed until it reaches the quarter-stroke, when the largest opening of the port is required to supply the engine with steam at full pressure, which will then be maintained as long as the ports are open, and as the motion decreases the weights drawn toward the center will cause the movement of the segment and cam back to their normal positions.

rlhose skilled in the art will readily see and understand the advantages of the above-described constrnction as to its utility over what is in common use, and especially is it adapted lo be of use in reciprocating-engines running at high rates ofspeed; that it is positivein its action as well as automatic; that there is no unnecessary movement or travel of the valves, and that the expansive force of the steam can bc utilized when the engine is not overloaded.

I am aware that Valve-gear for cut-off, regulated by a governor directly secured to the crank-shaft of an engine, and having centrifugal weights, wit-h springs, racks, and pinion, is not new, and I do not claim for such devices, broadly. I am also aware that valve-gear for cut-oti`s actuated by cams secured to the crankshaft ofthe engine,with weights, springs, pinion, and movable racks, has also been used, and I do not claim for such device, broadly; but

Having thus described my invention, what I claim, and desire to secure by Letters Patent,

l. The combination, in a governor-valve gear,of the movable segment-cam E, pinion D, having the radially-extending arm D', and its curved slot d therein, with the bolt d", friction-rollend', wheel A, and engineshaft A', substantially as described.

2. The centrifugal weights C C, racks B', springs B, and pinion D, having arm D,in combination with the segmental cam E,construct ed and operating substantially as described.

3. The centrifugal weights C C, racks B', springs B, pinion D, having the slotted arm D' andsegmental cam E, moving in the circle E', in combination with the cam F, having slot'e, as described.

4. The Valve-stems fi and 7c, having the friction-rollers h and 7L', traveling in groovef, in combination with the" links and m, having turn-buckles n n thereon, substantially as de scribed.

5. The combination, in a governor-valve gear, ofthe wheel A,secured to shaft A', having upon one of its sides the toothed pinion D, its slotted arm D', racks B', springs B, weights C, guide-rods a', and rods b, with the segmentcam E, cam F, groove f, valvesteins z' and lf, and their friction'rollers h h', arranged and operating upon the other, substantially as and for the purposes described. A

In testimony whereof I affix my signature in presence of two witnesses.

SAMUEL E. CRAVFORD.

W'itnesses:

J. P. STONE, G. F. HORNER. 

